Technical Field
Embodiments of the invention relate generally to power plant technology and, more specifically, to a system and method for reducing carbon dioxide emissions from a flue gas.
Discussion of Art
Many electrical power plants combust fossil fuels in order to generate heat, which in turn is used to power an electrical generator via a steam turbine. The combustion of fossil fuels, however, generates large amounts of carbon dioxide (“CO2”). Accordingly, due to the increased concern that CO2 may be contributing to global warming, many fossil fuel based power plants now attempt to reduce CO2 emissions by recapturing and storing CO2 via “carbon capture” technologies.
One such technology is a Fully Integrated Regenerative Calcium Cycle (“FIRCC”), which is a post-combustion system that utilizes two reactors, e.g., a carbonator and a calciner. In the carbonator, CO2 from the flue gas reacts with lime, or other carbon absorbing compound, to form limestone. The limestone is then sent to the calciner where it is heated and converted back into lime and CO2 via an endothermic calcination reaction. The CO2 is then captured and stored and the lime is returned back to the carbonator.
Presently, many fossil fuel based plants that implement FIRCC systems utilize calciners that rely on a transport gas, e.g., flue gas, to mix the limestone with heat-transferring particles that heat the limestone within the calciner. Many such calciners, however, typically do not achieve an optimal mixing of the heat-transferring particles with the limestone, which in turn, may reduce the efficiency of the calciner with respect to converting the limestone back into lime and CO2. Moreover, many such calciners are not hermetically sealed, and therefore, leak limestone, heat-transferring particles, and/or CO2, which in turn may also decreases the efficiency of the calciner with respect to converting the limestone back into lime and CO2, and/or the efficiency of the FIRCC system as a whole. Additionally, such non-hermetically sealed calciners may also have high air ingresses which, as used herein, refers to the amount of air entering into the calciner from the environment surrounding the calciner.
In view of the above, what is needed is an improved system and method for reducing carbon dioxide emissions from a flue gas.